Redox Reactions

• What are redox reactions?

  Reactions in which oxidation and reduction both take place at the same time
• What are the key components covered in redox reactions?

  • Displacement reactions
  • Ionic equations
  • Half equations
• What is one meaning of oxidation?

  The gaining of oxygen
• What is one meaning of reduction?

  The loss of oxygen
• If aluminum reacts with oxygen to form aluminum oxide, what happens to aluminum?

  It is oxidized
• What happens to aluminum if we take away the oxygen from aluminum oxide?

  It is reduced
• What does the mnemonic "oil rig" stand for?

  Oxidation is loss, reduction is gain
• If a magnesium atom loses two electrons, what does it become?

  A magnesium two plus ion
• What happens to magnesium if it gains two electrons back?

  It is reduced
• Why do oxidation and reduction reactions usually occur together?

  Because if one substance loses electrons, another must gain them
• What are redox reactions also known as?

  Reduction oxidation reactions
• What happens when magnesium reacts with dilute acid?

  Magnesium loses two electrons and is oxidized
• What do hydrogen ions do in the reaction with magnesium and dilute acid?

  They gain electrons and are reduced to hydrogen gas
• What is a displacement reaction?

  A reaction where a more reactive metal displaces a less reactive one
• In the reactivity series, which metal is more reactive: calcium or iron?

  Calcium
• What happens when calcium is added to a solution of iron sulfate?

  Calcium displaces iron to form calcium sulfate
• What are spectator ions in a reaction?

  • Ions that do not change during the reaction
  • They remain in the solution
  • They can be removed from the ionic equation
• How can ionic equations be simplified?

  By removing spectator ions
• What are half equations used for?

  To show the gain and loss of electrons for each element
• How do you write a half equation for calcium?

  A neutral calcium atom goes to form a calcium two plus ion and loses two electrons
• How do you write a half equation for iron?

  The Iron II plus ion goes to form an iron atom and gains two electrons
• How can you check if the overall charge balances in half equations?

  By ensuring the total charge on each side is the same
• What should you do if the overall charges on each side of a half equation aren't the same?

  Check the placement of your electrons
• What is the overall process of writing half equations?

  1. Write the ionic equation for one element.
  2. Add electrons to balance the charges.
  3. Ensure the overall charge is the same on both sides.